Fossick for Thundereggson Tamborine Mountain

Uncover some magical, mystical thundereggs by undertaking some fun fossicking at Thunderbird Park on Tamborine Mountain!

So if you think that wielding a pick or shovel sounds a little like hard work, then think again. You'll enjoy this unique activity, and it will be particularly rewarding when you discover one of these ancient gemstones.

So what exactly do you need to look for?

However, whilst cut and polished thundereggs are egg-shaped and have some spectacular hues and multi-coloured designs of quartz, amethyst, and other silicas, they don't look like this in the ground.

The outside of a thunderegg is typically red-brown in colour, and has a ribbed or bumpy pattern.

On entry into the open-cut mine, you'll be given a safety induction, and will be briefed on how and where to find them. And you'll see several 'raw' examples, too, to help differentiate them from regular rocks.

Thundereggs were formed on this Gold Coast Hinterland property on Cedar Creek over 300 million years ago, as a result of ancient volcanic activity in the region.

The entry cost to Thunderbird Park includes all necessary equipment to fossick - such as mining permit, pick, shovel, canvas bag - and you can keep all the thundereggs that you find. Admission allows you to fossick all day if you wish.

Note the additional cost (see Fast Facts) if you choose to have the master rock cutter polish your eggs.

You'll want to get at least one cut & polished, as the rockcutter uses specialised equipment not found in your average backyard shed at home.

And, unless a thunderegg is polished, it looks pretty much like a rock, which makes the entire fossicking exercise fairly pointless!

A number of other activities are also available at Thunderbird Park, including bushwalking, horseriding, and the recently opened attraction, Adventure Parc.

Here's the simplest explanation for how thundereggs were formed:

Steam and gases are commonly trapped in volcanic lava as it cools, forming large bubbles. Silicas (minerals) line the inside of the bubble, and eventually crystallise to form quartz.

The now-hardened 'bubble' may crack or split, often as a result of gas pressure, and this provides an opening to its hollow centre.

Over thousands of years, water enters the 'bubble' opening and deposits further layers of silicas or minerals in the cavity until it is completely filled.

These multi-coloured silicas then crystallise into quartz, chalcedony, amethyst and agate; the different mineral traces providing a brilliance of colours including brown-red, pink, yellow, white, gray, yellow and green.

Thundereggs are not formed in every volcanic eruption - the lava needs to be rich in silica so it can crystallise. Such was the case with ancient volcanic activity in the Tamborine Mountain area.

As a result, one of Australia's richest sources of thundereggs was formed right here on the Gold Coast, where they lay undiscovered until 1967, at which stage a private open-cut mine was established.

FAST FACTS

Cost

Adults & kids aged 13+ years: $23 per personKids aged 12 years and under: $12 per personCost includes all fossicking equipment.Cutting & polishing cost is not included, and is charged @ $2.20 per square inch.

Facilities

Toilets, cafe, picnic grounds, bushwalking trails.Horseriding and admission to Adventure Parc are available at an additional cost.

Wet Weather

The mine is closed in wet weather.

Operating Hours

7 days a week, from 9am to 4pm (last entry to mine 2.30pm).Closed on Christmas Day and Good Friday.

Duration

1-2 hours is usually enough for most people. Note that you may need to wait for up to an hour to have your thundereggs polished in busy periods (although there are other activities to do while waiting).